Shears



June 3, 1941- R, H. BOARIISMAN 2,244,638

SHEARS I Filed Aug. 2, 1940 2 Sheets-Sheet 2 j "x 55' I Ji INVENTORfatented June 3, i941 UNITED STATES" PATsnr ctr-ice 2,244,638

to The Stanley Works, New Britain, Conn, a corporation of- ConnecticutApplication August 2, 1940, Serial No. 349,893

8 Claims.

This invention relates to automatic or power driven cutting toolscommonly called shears suitable especially for cutting sheet metal.

One object is to provide a form of mechanism which is strong butcompact, simple, of few parts and relatively inexpensive to constructand main tain. Simplicity of construction and ease of as sembly andrepair tend to long life.

Another object is to secure smoothness, ease of operation and freedomfrom unnecessary vibration. This latter feature also tends to minimizewear and permits a maximum. amount of work because of a minimum loss oftime in break downs and because of a minimum strain on the operator.

Another object is to provide a tool which can be used efiectively to outalong curved as well as straight lines, either near the edge or near thecenter of a sheet. I

Another object is to provide a construction embodying an efiicientelectric motor drive;

Another object is to provide reliable mechanism well balanced andsuitable for being conveniently held in the hand while operating.

- Another object is to secure adequate lubrication without damage to themotor.

Another object is to so arrange the parts that the operator can clearlysee the line ofcutting. Such mechanism should be relatively light inweight and well balanced whenin use.

Details of the preferred formof the device will be found shown in theaccompanying two sheets of drawings.

Fig. 1 is a side View and partial section ofthe' Theinvention isespecially adapted for a hand held tool driven by a suitable electricorpn'eumatic motor. The casing l contains a suitable motor H withbearings l2 and'13. One'e'nd H of the casing is preferably detachablysecured to the main part of the casing by a; number of screws or boltsI5 and carries one of the motor bearings.

The casing has a handle member is with means at I! for connection with asource of power and :a switch or start and stop member l8 in aconvenient location so that the tool can be held in a balanced positionand when so held with a worm 21. on the lower end of the motor shaft 28beneath the shaft 23. It will be noted that the motor shaft is inclineddownwardly and forwardly relative to the vertical axis of the l head ofthe casing and that the bearing I3 is interposed between the motorchamber and the gear chamber. As a result there is little chance of thelubricant in the gear casing working back into the motor casing where itis likely to injure the motor.

The stationary cutter 313 is carried by the free end" of a hook-shapedyoke or anvil 3 l The otherend 32 is secured to the lower end of thehead by two screws or bolts 33 and 34. The cutter is laterallyadjustable by a screw 35.

The reciprocable cutter 36 is carried by the bar 31' being clamped to itby a screw 33 and backed up by a screw 39. The upper end M] of the bar31 has a ball bearing unit tl mounted in it and supported on theeccentric end 52 of the drive shaft 23 in the chamber 253. The lower endof the bar 31 is slidably guided in a channel 43 in the cylindricaloscillator bearing member 44. The edges of the bar 31 preferably haveoil grooves 45 fed from a hole 4% which is above the upper edge of theoscillator 14. v The grooves 45 lead to the edges of the channel 53. Theoscillator is supported in :a cup-like bearing il which can be cast inthe head of the casing and finished inside in a suitable manner so as toprovide a smooth and wear resisting surface for the oscillator.

The anvil member 3| of course must be very strong to resist the stressesto which it is subjected. Preferably the upper part of this anvilprovides a side bearing wall tfi'aga'inst which the lower end of themovable cutter carrier 31 travels. This ensures an accurate lateralrelationship between the two cutter blades which is essential forsatisfactory operation especially at the high speeds for which thesetools are designed;

It will b'e'noted that the movable cutter not to be followed, and thereis but little chance of Also the cutting the sheet jamming in the tool.point is outside of the housing area to allow for trimming close to thevertical sheet of material.

This arrangement of the eccentric connection of the cutter carrier withthe drive shaft and the oscillating support and guide closely adjacentthe cutting point ensures very smooth operation with but littlevibration thus minimizing the strain on e the operator and on the tool.

In Fig. 6 is shown a modified form of cutter carrier bar 3?. The upperend 46 is mounted on the eccentric end of the drive shaft as previouslydescribed. The lower part is provided with an elongated opening 43 whichconstitutes a guideway for the ball or roller bearing unit 44' which issupported on a stud or bearing 41' in the head of the tool.

Inside the cover plate 22 is preferably placed a bronze wear plate about.050" in thickness and of the same area and shape as this cover plate 22and held in place by the cover plate screws.

The enlarged View, Fig. 7, shows the direction and path 55 of movementof a point on the movable cuttlng blade 35 whereby a slicing actiontakes place rather than a straight line shear action. The dotted lineposition of the cutter is substantially 180 removed from the full lineposition.

To better balance the tool against troublesome vibration at high speed,the worm gear 26 may be provided with a counterweight to at leastpartially offset the inertia of the cutter carrier bar. Such effect iseasily attained by cutting a recess or groove in the part of gear 26which is angularly alined with this crank or eccentric 42. Both thestationary and movable parts are made as light in Weight as isconsistent with the work to be performed. The motor and gear housingsare. preferably of some light Weight metal or material such as aluminumor Dow metal.

Although this invention has been showniembodied in a portable hand tool,certain features of the broad invention may be applied also to bench andpedestal types of machines. The portable tool illustrated may be'mountedin a cradle for use as a stationary or bench type machine and suchcradle may be supported on a table or bench or hung from above to placethe stationary cutting blade below the moving blade. The cradle will ofcourse be designed to provide clearance for the handle whichlongitudinally overlaps the motor casing.

' Other modifications in details may be made within the scope of thisinvention except where the claims are especially limited to thepreferred form of the invention. The cutting blades may be laterallyoffset a greater amount than is shown by Fig. 4 of the drawings;Forexample, the line of cutting may be substantially flush with the sideof the gearhousing so as to be visible from above this housing, or theseblades may be laterally ofiset still further and beyond the housing..'As

shown in Fig. 2 the handle I6 is laterally offset from the axis of themotor until it is substantially alined with the center of gravity of thetool, the lateral offset of the handle being desirable because thelateral offset of the anvil and cutting blades causes the center ofgravity to be moved to one side of the motor axis.

It has been found desirable to have the motor located close to the workto facilitate cutting and for this reason the worm 27 is located belowthe worm gear 26. However in order to provide additional chip clearancewhen the motor is located close to the work, that is clearancesufiicient to allow strips of cut material to roll up, the rear endportion of the motor is raised by giving the motor axis the upwardinclination illustrated away from the worm and gear. Such an upwardinclination to the motor shaft of between 10 to 20 to the horizontal isbelieved to facilitate cutting and reduce the strain on the operator.

, I claim: 7

1. Power driven shears comprising a housing, a transverse drive shaftrotatably supported therein and having'an eccentric, a stationary cuttercarried by the housing, an oscillator rotatably supported in the housingbetween said cutter and said shaft, and a movable cutter carrier havingone end mounted on said eccentric and a portion slidably supported insaid oscillator adjacent the stationary cutter.

.2. Power driven shears comprising a housing, a drive shaft rotatablysupported therein and having an eccentric, a stationary cutter carriedby the housing, an oscillator rotatably supported in the housing betweensaid cutter and said shaft and having an open channel cut in one face, amovable cutter carrier having one end mounted on said eccentric and aportion slidably supported in the channel of said oscillator adjacentthe stationary cutter and a cover plate holding the cutter carrier inplace in said channel.

3. A shearing device comprising a housing having a cavity, with anopening at one side, a detachable cover plate for said opening, atransverse shaft having spaced bearings in the upper part of the housingcavity, a substantially vertical cutter carrier bar having a cutterblade at its lower end and having an eccentric connection with the endof the shaft adjacent the upper end 1 of said opening, a motor having ashaft inclined downwardly and forwardly beneath said transverse shaft, aworm and gear connection between said shafts, a stationary cutter bladesupported by the housing and cooperating with the cutter blade, and aguide member for the carrier bar mounted in the lower end of the cavityin the housing adjacent the cutter blade and permitting the carrier barto move up and down in the cavity and to tilt about the axis of saidguide, said cutter carrier bar and said guide being readily removablewhen the cover plate is removed, said cavity being adapted to holdlubricant for the transverse shaft, the cutter carrier barand the guidemember.

4. Power driven shears comprising a housing, a transverse drive shaft inthe upper end of the housing and having an eccentric, a stationarycutter on the lower end of the housing, an'elongated vertically disposedmovable cutter carrier having its upper end mounted on the eccentric andcarrying acutter at its bottom end, and a guide member freely engagingthe lower part of the movable cutter carrier whereby a limited verticaland horizontal motion of the cutter is permitted.

5. Power driven shears comprising a housing, a transverse drive shaft inthe upper end of the housing and having an eccentric, a stationarycutter on the lower end of the housing, an elongated vertically disposedmovable cutter carrier having its upper end mounted on the eccentric andcarrying a cutter at its bottom end, and a cylindrical member mounted inthe lower end of the housing and having a central channel in its faceextending from edge to edge thereof and adapted to guide smoothly aportion of the lower end of the carrier whereby limited vertical andhorizontal motion of the cutter is permitted.

6. In a power driven shears of the type for cutting either straight ,orcurved lines, actuating means, a gear housing, a reciprocating carrierbar for a movable blade, an eccentric for actuating said carrier, anoscillator guide for said carrier bar constituting the pivotal axisabout which said carrier bar oscillates, a guide opening in saidoscillator in which the carrier bar slides, said oscillator guide havingarcuate bearing surfaces laterally of said guide opening and within saidgear housing.

7. A shears comprising a motor and shaft, a stationary cutting blade andsupport therefor located at one side of the motor shaft, a second shaftlocated transversely of the motor shaft and the opposite side from thestationary blade, spaced bearings for said second shaft, means betweensaid bearings for driving the second shaft from the motor shaft, anoverhanging crank, a connecting rod actuated by said crank and carryinga movable blade cooperating with the stationary blade, a rockingcross-head or guide located between the crank and movable blade andadjacent the latter, and means on the second shaft for counterbalancingthe thrusts of said connecting rod.

8. A 'power driven shears comprising a motor and housing therefor, amotor shaft having on the forward end portion thereof a worm, a wormgear driven by the worm and mounted on a transverse shaft, bearings forsaid shaft, an eccentric on said shaft, a rod mounted on said eccentricand carrying a movable cutting blade, a stationary cutting bladeattached to the motor housing, the improvement which enables the motorto be located close to the work to facilitate cutting and whichcomprises locating said worm below said worm gear.

RALPH H. BOARDMAN.

